More specifically, this study is intended to provide some answers to questions, such as (1) could kinin analogs be useful to enhance brain tumor delivery of another class of chemotherapeutics, namely doxorubicin (DOX); (2) is there a size dependency of the BBB opening induced by B2R agonists; (3) could the transient pharmacological opening of the BBB by B2R agonists lead to increased formation of breast cancer brain metastases; and 4) what is the long-term impact of prior brain radiotherapy on the kinin B2R-mediated increases in BBB permeability. The gene discussed is BDKRB2; the disease is breast cancer.